Feast Your Eyes on My ASR-33 Teletype Terminal

I just took possession of the most amazing ASR-33 Teletype Terminal that's equipped with a keyboard, printer, paper tape reader, paper tape punch, and copy holder.

A few months ago, I presented an online course on "Basic Industrial Control Systems" on the Design News website. As part of that course, we discussed the computer systems of yesteryear, and I mentioned the fact that I would really like to get my hands on an old teleprinter (also known as a teletypewriter, teletype, or TTY).

These electromechanical typewriters were used to send and receive typed messages from point-to-point. They were also used as input/output devices for early mainframe computers. Furthermore, for the purposes of creating programs offline, you could get them equipped with paper tape and/or punched card readers and writers.

Well, a few weeks ago I received an email from Leo Sieben, who hails from Memphis, Tenn. Leo had been watching my course, and he thought to himself: "I have an old ASR-33 teletype in storage; I wonder if Max would be interested in it?"

So Leo emailed me, and I jumped up and down in excitement (it's possibly that a little high-pitched squealing was involved) and told him that I would be very interested in this little beauty. Thus it was that last weekend found me taking a road trip to Memphis to meet up with Leo in his lair. The photo below shows Leo standing with his beloved teletype:

As you can see, this little scamp (the ASR-33, not Leo) has a keyboard, printer, paper tape reader, and paper tape punch (there's also a copy holder, which isnít shown in this picture because we'd already taken it off prior to opening the beast).

After eating lunch at Fino's, which Leo enthusiastically proclaims to be the best deli in Memphis, we removed the cover to peruse and ponder the internals as shown below:

While the cover was off, with no small amount of trepidation, we decided to power-up the beast, resulting in a conversation that went something like this:

And he did. And the motor started chuntering away to itself. And everything was well with the world. The rubber drive belts look almost as good as new, which is pretty amazing when you come to think about it. And, even though this little scamp has been in dry storage for 30 years or so, even the print ribbon still works. We tried entering a few words on the keyboard. The type is faint on the paper, but it's there. Now I need to get a new ribbon.

Also, the paper tape punch works. We turned it on and then keyed-in a few characters on the keyboard and watched the holes being punched in the tape. It was all very satisfying indeed.

Two things that donít work at the moment are the Carriage-Return/ Linefeed key and the Bell key. However, to be honest, after 30 years, I'm amazed that everything works as well as it does.

I've also been reacquainting myself with some of the little details that I'd forgotten over the years. For example, consider the four translucent plastic control buttons sitting over the paper tape punch as shown below:

You would be forgiven for thinking that these were each connected to individual electrical switches under the cover, but then you'd be forgetting the electromechanical nature of this thing. When we lift the cover, we are presented with the following sight:

Observe the metal "paddle" on the right-hand-side, with two flat plates: one at the top and one at the bottom. Two of the spring-loaded translucent plastic buttons are used to toggle this paddle from one state to another, thereby effecting both electrical and mechanical changes.

Last, but certainly not least, we see my ASR-33 ("my precious") in its new home sitting outside the door to my office (this photo was taken before I added the rolls of paper and tape back in). Why outside my door? Because I want everyone walking past to feast their eyes on this little beauty and to drool over it and lust after it (cue maniacal cackling sound effect).

So, what's the next move? Well, first of all, since Huntsville, Ala., has been so involved in computers for decades (due to its large presence in the military and space and engineering fields), there must be someone around who used to service and maintain teletypes. All I have to do is track them down and see if they would be interested in coming and walking me through the maintenance procedures. (If you live in Huntsville and know someone like this, please contact me at max.maxfield@ubm.com.)

Once I've had my ASR-33 serviced, I would like to connect it to the computer in my office. I'm thinking of having a little HyperTerminal window in the corner of one screen. When someone walks by, I can type a simple message like "Hello There!" and hit the return key, thereby causing this message to print out on the teletype -- and punch out on the paper tape -- with a cheery ring of the bell thrown in for good measure. The bell will attract the person's attention causing him to move closer and peer down, at which time I might follow up with a merry quip along the lines of: "What? You wore a red tie with that shirt???"

Communication with this teletype is based on a 20mA current loop. So the first thing I will need will be a bidirectional current loop to RS-232 converter. Now, I could run an RS-232 cable to my tower computer (which still has a serial interface), but the SNAP wireless modules from Synapse Wireless also support RS-232. Based on this, I'm thinking that it should be relatively easy to use a wireless link to connect my compute to the teletype. Watch this space...

Hi, I have fond memories and some not so fond memories of that ASR33. One might benefit from my experience. I used it mainly as an I/O terminal to a Data General Mini Computer, Nova 3 and 4's...where it worked fine loading bootstraps and user input/output. When microprocessors came out in the middle 70's, I needed the ultimate in reliability for reading 8 KB paper tapes for Basic and other Software. The BER, Bit Error rate was less than desired, so I found the ASR-33 delighfully easy to take apart, clean, re assemble etc generall R&R, but often the BER rate when up surprisingly. The correct weight lubricant was most important to get ultra reliable operation.. and the correct weight lubricant was much lighter than I would have ever expected. I don't remember specifically what I used, but I believe it was specified in the manual. Likely the machine will have to be cleaned and likely relubricated.. so pay attention to using the lightest lubricant you can find or specified .. MrPixel@gmail.com used the machine at was was then called Highway Safety Research Institute, Ann Arbor Michigan. Best Wishes Leigh

Fond Memories indeed. I worked at a place that used ASR33s as the interface to Data General DG3s (mini computers from yesterday).

Before that, I had a Creed set up to run RTTY (Radio Teletype) on both HF and VHF. For a while, I was broadcast officer for a amateur radio club (HAMs) and was responsible for doing a weekly RTTY broadcast. The problem is when you mis-type a character, you can start from scratch (again!) or just live with it. Broadcast ran for around 5-10 minutes at 50 baud. You can imagine the amount of paper tape consumed in the process. Computers fixed all that.

Setting these up is not for the feint hearted. Max, get someone to do it for you. I knew a bloke who could listen to a TTY and tell you what was being transmitted - kind of like a complicated Morse code.

I first used these in high school, connected over leased current loop lines (Ma Bell) to a shared computer in an adjacent school district. When I was in college (30+ years ago), these were all over, some hardwired, some on Anderson Jacobsen 110 baud modems in wooden boxes. The ASR33s were under service contract. When one would break, the service provider would bring a complete replacement machine, at no charge, provided they did NOT have to take the old one back. It seems that as these machines became obsolete, they had a warehouse filled with ones fresh off lease. Our broken machines were carted away to a room in the basement of the Buchard Building, housing EE and Physics. Soon we didn't bother calling service, as it was faster to scavenge parts from the growing pile in the basement. Every once in a while, rumaging through my junk at home, I come upon a motor start relay from an ASR33.

@n1ist: The printer can be removed and flipped over to fix it, but remember that the punch and reader are both driven from the print mechanism and are connected.

I now have links to all the maintanance manuals online ... so it may come to that -- but I still live in hopes of finding someone local who used to maintain these, because they coudl do it so much faster and more efficiently...

@JeffL_2: ...but I couldn't afford the space anymore and it was not in good enough shape to be worth the trouble and besides all the computer museums said they wouldn't be interested even if it were new fresh in the box.

I simply cannot believe that anyone wouldn;t want one fresh out of the box -- especially museums ... it's a sad world...

@Rick I used to do that manually with my old Baudot machines. You just needed to know what characters to use to get the right holes in the tape. for instance "Z" gave the two outside holes and "C" gave the 3 inside holes (only 5 bits remember!) so to get an "O" on the tape you'd key CZZZC. The problem as I remember was getting a space with no holes punched in the tape. Of course Max's machine is ASCII so that would probably make it easier. And with 7 holes in the tape you could do 7x5 characters instead of my 5x5 ones. I could do a program for this in BASIC quite easily, just a lookup table really.